Multi well-plates, also known as microtiter plates or micro well-plates, are standard products in clinical and research laboratories. A multi-well plate is a flat plate with multiple wells used as individual test tubes. The most common multi-well plates include 96-wells or 384-wells arranged in a rectangular matrix. ANSI has set standardized dimensions and SBS footprints for well-plates. For example, a 96-well plate has 8 rows and 12 columns of wells centered 9 mm centerline-to-centerline. A typical 384-well plate includes 16 rows and 24 columns of wells with a centerline-to-centerline distance of 4.5 mm. Multi well-plates with 1536 wells and higher are also available. Some multi well-plates are designed to hold larger volumes than the standard multi well-plate, yet maintain the standard centerline-to-centerline dimensions. These well-plates are taller and are commonly called deep well-plates.
In a laboratory, multi well-plates are filled with various liquid samples, and it is routine to transfer liquid samples from one wellplate to another in order to implement assays or store duplicate samples. It is also routine to transfer liquid reagents or samples from a common reservoir to either a standard multi-well plate or a deep well-plate. Often, hand-held, multi-channel pipettors, with 8, 12 or 16 disposable pipette tips mounted thereto, are used to draw some or all of the liquid from a set of wells in one wellplate and transfer aliquots into another set of wells in the same wellplate or another wellplate. Pipettors and pipette tips come in various sizes in order to accommodate different volumes of liquid transfer. In order to produce a high volume of prepared multi well-plates, automated liquid handling machines have been developed to provide much higher throughput than a technician, even one using a multi-channel pipettor. In the art, there are several types of automated liquid handling machines to automatically fill multi well-plates. Such automated liquid handling machines typically use sophisticated Cartesian robots for positioning the disposable pipette tips, while shuttling well-plates from storage and into position for liquid transfer. It is common for these automated liquid handling machines to use removable and replaceable pipetting heads in order to accommodate various sized pipette tips.
Most of these automated liquid handling machines are rather expensive, and also quite large. Many include sophisticated computer control which requires extensive training, as well as set up and programming. Such automated, high-throughput systems are not practical for some applications. In order to address this need, the prior art includes, e.g., a simultaneous 96-well manual pipetting system. This fully manual system includes an array of pipette tip fittings matching the dimensions of a standard 96 well-plate, and aspirates and dispenses liquid from 96-disposable pipette tips simultaneously. The pipette tips are mounted to the 96-tip fittings using a levered mechanical mechanism. Because the system is fully manual, it lacks the ability to program precise protocols and liquid transfer amounts. On the other hand, electronic hand-held pipettors and automated liquid handling systems can be programmed to aspirate a precise volume of liquid reagent or sample and then dispense the aspirated volume, sometimes as a series of equal volume aliquots in successive dispensing operations. Programmable electronic hand-held pipettors and automated liquid handling systems can also be configured to do quite complex pipetting operations, such as mixing, repeat pipetting, diluting, etc.
While programmable, automated liquid handling systems have many desirable features over a fully manual 96-well liquid transfer system, they are generally too large and expensive for certain laboratory applications. To address this issue, the Assignee of the present application has developed a manually directed, electronic multi-channel pipetting system having a pipetting head with a plurality of pipetting channels arranged in a two-dimensional array of rows and columns, preferably 96-channels arranged in an array of 8 rows and 12 columns correlating to a standard 96 well-plate. The system is described in Assignee's co-pending patent application entitled “Manually-Directed, Electronic Multi-Channel Pipetting System”, application Ser. No. 13/099,782,by Julian Warhurst, Gary Nelson and Richard Cote, filed on even date herewith, Publication No. U.S. 2011/0268627 Al, published Nov. 3, 2011, and incorporated herein by reference. In the Assignee's manually-directed, electronic 96-channel pipetting system, the pipetting head is mounted to a movable carriage that is attached to a tower containing a drive system for the pipetting head. A deck with at least one, but preferably two or more, wellplate nesting receptacles is located in front of the tower and is accessible by the pipetting head. The tower contains a drive system to raise and lower the pipetting head to aspirate and dispense reagents or samples in the well-plates or reservoirs placed in the nesting receptacles.
The Assignee's system also includes a control handle and a menu-driven software programming interface that is the same or quite similar to the control handle and programming interface on hand-held electronic pipettors sold by the Assignee, see e.g., the disclosures in U.S. Pat. No. 7,540,205 entitled “Electronic Pipettor”, issuing on Jun. 6, 2009, based on U.S. patent application Ser. No. 11/856,231 by Gary E. Nelson, George P. Kalmakis, Kenneth Steiner, Joel Novac, Jonathan Finger, and Rich Cote, filed on Sep. 17, 2007, and incorporated herein by reference; and “Pipettor Software Interface”, application Ser. No. 11/856,232 by George P. Kalmakis, Gary Nelson, Gregory Mathus, Terrence Kelly, Joel Novak, Kenneth Steiner and Jonathan Finger, filed Sep. 17, 2007, assigned to the Assignee of the present application and incorporated herein by reference, now U.S. Pat. No. 8,033,188 B2, issued Oct. 11, 2011. One of the benefits of the similarity is that users comfortable with the Assignee's hand-held pipettors are able to easily crossover to use the Assignee's manually assisted, electronic 96-channel pipetting system. In the Assignee's 96-channel system, however, the control handle is mounted to a load cell attached to the carriage for the pipetting head. The load cell detects force exerted on the control handle and outputs a corresponding signal to an electronic motor control system. In use, the user grabs the control handle in a manner similar as to when using a hand-held electronic pipettor, and exerts pressure on the control handle so that the electronic motor control system moves the pipetting head relative to the well-plates and reservoirs on the deck. In the preferred embodiment, the tower contains a motorized, z-axis drive mechanism for vertically raising and lowering the pipetting head with respect to the wellplate deck, and a motorized x-axis drive mechanism for moving the tower and pipetting head laterally, both being driven in response to sensed force exerted on the control handle. If the user presses on the control handle from left to right, the tower along with the pipetting head moves from left to right. If the user pulls the control handle upward, or pushes downward on the control handle, the z-axis drive mechanism raises or lowers the pipetting head accordingly.
While Assignee's manually directed, electronic 96-channel pipetting system preferably incorporates the user interface and menu-driven software similar to Assignee's single-channel and multi-channel, hand-held pipettors, other aspects of a 96-channel pipetting system must be handled quite differently.